Hi,
I was using perf record to run various tests and I
realized perf output was rather misleading.
If you sample a noploop program wich runs for 10s:
$ perf record -F 1000 noploop 10
You expect a number of samples around: 10,000.
Now if you divide the rate by 4:
$ perf record -F 250 noploop
On Wed, 2010-06-16 at 16:40 +0200, Stephane Eranian wrote:
> This leads me to another point. For per-thread sampling, why
> do we need to record mmap() events happening *outside* of
> the process? I can understand the exception of kernel modules.
How does that happen? The per-thread events should
On Wed, 2010-06-16 at 16:40 +0200, Stephane Eranian wrote:
> The reason is that perf reports an estimate based on the
> number of bytes written to the buffer divided by the minimal
> sample size of 24 bytes.
Right, we should change that based on the PERF_SAMPLE flags used. It
will remain an estim
On Wed, Jun 16, 2010 at 4:52 PM, Peter Zijlstra wrote:
> On Wed, 2010-06-16 at 16:40 +0200, Stephane Eranian wrote:
>> This leads me to another point. For per-thread sampling, why
>> do we need to record mmap() events happening *outside* of
>> the process? I can understand the exception of kernel
On Wed, Jun 16, 2010 at 6:41 PM, stephane eranian
wrote:
> On Wed, Jun 16, 2010 at 4:52 PM, Peter Zijlstra wrote:
>> On Wed, 2010-06-16 at 16:40 +0200, Stephane Eranian wrote:
>>> This leads me to another point. For per-thread sampling, why
>>> do we need to record mmap() events happening *outsid
On Wed, 2010-06-16 at 18:41 +0200, stephane eranian wrote:
> On Wed, Jun 16, 2010 at 4:52 PM, Peter Zijlstra wrote:
> > On Wed, 2010-06-16 at 16:40 +0200, Stephane Eranian wrote:
> >> This leads me to another point. For per-thread sampling, why
> >> do we need to record mmap() events happening *ou
A bug was introduced by commit c45c6ea2e5c57960dc67e00294c2b78e9540c007.
Perf record was scanning /proc/PID to create synthetic PERF_RECOR_MMAP
entries even though it was running in per-thread mode. There was a bogus
check to select what mmaps to synthesize. We only need all processes in
system-wi
Em Wed, Jun 16, 2010 at 08:59:01PM +0200, Stephane Eranian escreveu:
> A bug was introduced by commit c45c6ea2e5c57960dc67e00294c2b78e9540c007.
>
> Perf record was scanning /proc/PID to create synthetic PERF_RECOR_MMAP
> entries even though it was running in per-thread mode. There was a bogus
> ch
